What does it mean?
P1197 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: O2 Sensor Heater Circuit (Bank 2-Sensor 1) Electrical Malfunction .
Symptoms
- Check engine light on shortly after a cold start
- Bank 2 stays in open loop longer, so mixture control is uneven between banks
- Rich running and extra fuel consumption during warm-up
- Slight roughness at idle while cold
- Emissions readiness monitors remain incomplete
- Fuel trims may differ between the two banks during warm-up
Likely causes
- Open or shorted heater element inside the bank 2 upstream sensor
- Damaged heater wiring on the bank 2 side, which often runs closer to the exhaust manifold
- Corroded or moisture-contaminated connector on that bank
- Blown fuse or a failed relay supplying the heater circuits
- Poor ground connection for the bank 2 heater circuit
- Control module heater driver for that channel failed
- Harness damaged during previous exhaust or engine mount work
How to fix it
- Read all codes and check whether only bank 2 heater codes are present, which suggests a local wiring or sensor fault rather than a shared fuse
- Measure heater element resistance at the bank 2 sensor and compare it with the bank 1 sensor
- With the ignition on, verify heater supply voltage at the bank 2 harness connector
- Check that the module pulls the heater control wire to ground when the engine runs
- Inspect the bank 2 harness for heat damage where it passes the manifold, and the connector for corrosion
- Repair damaged wiring, clean terminals and reroute the harness away from hot surfaces
- Replace the bank 2 upstream sensor if its heater is faulty, then clear codes and confirm both banks warm up together